Imagawa W, Bandyopadhyay G K, Wallace D, Nandi S
Cancer Research Laboratory, University of California, Berkeley 94720.
Proc Natl Acad Sci U S A. 1989 Jun;86(11):4122-6. doi: 10.1073/pnas.86.11.4122.
Epithelial cells obtained by collagenase digestion of mammary glands from virgin BALB/c mice were cultured in collagen gels in serum-free basal medium containing insulin (10 micrograms/ml), to which lipids or growth factors were added. Synthetic phospholipids were added as liposomes. Dilinoleoyl phosphatidic acid or phosphatidylserine or epidermal growth factor stimulated multifold growth. The optimum mitogenic effect of the phospholipids was dependent upon the presence of a polyunsaturated fatty acid esterified to the sn-2 position of the glycerol moiety. Dilinoleoyl phosphatidylcholine also stimulated growth but was generally less stimulatory than phosphatidylserine or phosphatidic acid, and phosphatidylethanolamine did not stimulate growth. Studies using phospholipids radiolabeled in either the sn-2 fatty acyl group or the glycerol backbone showed that the relative effect of phospholipids on growth did not correlate directly with the extent of their incorporation into cellular lipid, indicating that phospholipid turnover was the more important determinant for mitogenesis. Analysis of phosphatidic acid-stimulated growth suggested that both cAMP-dependent and cAMP-independent pathways were involved. Thus, mitogenic phospholipids stimulate proliferation by activating (directly or indirectly) multiple growth-regulatory pathways in mammary epithelial cells.
通过胶原酶消化处女BALB/c小鼠的乳腺获得的上皮细胞，在含有胰岛素（10微克/毫升）的无血清基础培养基中的胶原凝胶中培养，向其中添加脂质或生长因子。合成磷脂以脂质体形式添加。二亚油酰磷脂酸或磷脂酰丝氨酸或表皮生长因子刺激了数倍的生长。磷脂的最佳促有丝分裂作用取决于酯化到甘油部分sn-2位的多不饱和脂肪酸的存在。二亚油酰磷脂酰胆碱也刺激生长，但通常比磷脂酰丝氨酸或磷脂酸的刺激作用小，而磷脂酰乙醇胺不刺激生长。使用在sn-2脂肪酰基或甘油主链上放射性标记的磷脂进行的研究表明，磷脂对生长的相对作用与它们掺入细胞脂质的程度没有直接相关性，这表明磷脂周转是有丝分裂发生的更重要决定因素。对磷脂酸刺激生长的分析表明，cAMP依赖性和cAMP非依赖性途径均参与其中。因此，促有丝分裂磷脂通过（直接或间接）激活乳腺上皮细胞中的多种生长调节途径来刺激增殖。
